The brown recluse spider is a small, venomous spider native to the central and southern United States. It typically has a light brown body with a distinctive violin-shaped marking on its back. Adult spiders are about 1/4 to 1/2 inch long, excluding their long legs. These spiders prefer dark, undisturbed areas such as attics, basements, and woodpiles. While their bites can be harmful, they are generally not aggressive and will only bite when threatened. If bitten, it is important to seek medical attention, especially if symptoms worsen.